Many firearms utilize magazines to hold ammunition. Such firearms include most semi-automatic firearms, which fire a single round when the trigger is pulled but automatically cycle through all necessary steps to prepare another round to be fired, and fully-automatic firearms, which fire a plurality of rounds when the trigger is pulled or held. Examples of such firearms are carbines, many pistols, and semiautomatic shotguns. Once the firearm exhausts its rounds from the magazine, it is necessary to remove the spent magazine and replace it with a loaded one to continue discharging the firearm. Generally, removing a spent magazine requires that the firearm operator depresses a magazine release button. The magazine then falls out of the chamber by its own weight.
Firearm users, especially military and law enforcement, are sometimes faced with situations requiring them to quickly replace the firearm's magazine. Such situations may reasonably endanger the user's life. Therefore, it is important that magazine stripping is reliable and does not become a hindrance. Even a small delay, such as fractions of a second, in unloading of a spent or malfunctioning magazine and re-loading a full magazine could have grave results on the firearm operator.
Competition shooters, such as those involved in high speed shooting and magazine reloading, are often rate-limited by a spent magazine that does not release from the firearm. Their entire performance is bottlenecked by a mechanical process with little to do with the sport itself. In order to avoid such a situation, many such shooters release the magazine while it still contains some rounds because a partially full magazine is heavier than an empty magazine. As such, the magazine drops easier from the firearm than a lighter empty magazine. However, this comes at a cost: the user cannot fire the maximum number of rounds in each magazine.
Many firearm users have developed techniques and skills to allow them to quickly strip a spent magazine out of the firearm after the magazine release button is depressed. These techniques include a sweeping motion with the free hand. Such a motion applies a quick push on the magazine, allowing it to be quickly stripped out of the firearm. This sweeping hand motion is a skill that can only be acquired through dedicated training. Another technique utilizes a quick twist of the firearm to impart centrifugal force to the magazine that is enough to make it slide out of the magazine well by the magazine's own inertia. Yet another technique more commonly associated with pistols involves rapid shaking of the firearm, which helps overcome minor friction and may impart some centrifugal force to assist the magazine falling out of the well. Each technique uses valuable time that in which the user is not firing, while possibly taking fire.
Further, even if these skills are mastered, a user could potentially mistake the motions, resulting in a failure to strip the magazine from the firearm quickly. Therefore, these skills are not reliable and have inherent risk. Yet the skills might not be necessary if magazine stripping becomes automatic, which would eliminate the need to develop special skills or techniques and ultimately would be expected to decrease the probability of failure.
Yet even further, firearm operators in dusty or sandy environments are faced with the challenge of dust or dirt getting into their firearms, especially onto the magazine or inside the magazine well. Presence of dust or dirt on the surface of the magazine may significantly increase the friction between the magazine body and the inside wall of the magazine well. This condition slows down the release of the magazine and the specialized skills discussed above may not be sufficient to release the magazine quickly. In extreme cases, the magazine may even hang inside the magazine well. Such a condition requires that the firearm operator uses his/her free hand to pull the magazine out of the firearm. Again, such a situation could have serious ramifications, including additional rounds being fired at the user before the user can neutralize his intended target, which increases the probability of being hit, endangering any missions and the user himself.
Continuous use of a firearm and its magazines will result in the increased temperature of both firearm and magazines. In some cases the magazines expand (swell) and become tightly wedged inside the magazine well. Ultimately this will increase the friction of the magazine against the firearm's magazine well, slowing or even stopping the magazine from falling out of the firearm without external influence.
In all of the above situations, removal of a spent magazine requires that the firearm operator pulls the magazine using the free hand which is a distraction and an extra effort that may literally endanger the firearm user's life. The net result is a decreased chance of a successful engagement.
Mercenier (U.S. Pat. No. 5,353,537) uses a technique wherein an ejection thread spring is added to each magazine, but is exclusively mounted at the bottom of the magazine or on the magazine plate of the magazine (col. 2, lines 54-63). However, this technique has several disadvantages. First, it only applies force from one edge of the magazine, which can apply appreciable torque, even resulting in a jam. Second, it will not function for any magazine wherein the magazine is not completely inserted into the magazine well during use such that the bottom of the magazine is flush with the bottom of the well. Third, the spring is partially inside the magazine, so it cannot be merely moved halfway up the magazine without severely limiting the number of rounds the magazine can hold as ammunition will not be able to be fed past the spring on the inside of the magazine, so the spring will effectively redefine the bottom of the magazine, only housing an empty cavity below itself.
Therefore, there is a need for a mechanism to assist in stripping a magazine from a firearm that is robust and adaptable to a plurality of firearms and magazines. Further, backward compatibility with firearms that have already been manufactured is highly desirable.